This invention relates to strainer assemblies for the drain openings of sinks, and, more particularly, to a strainer assembly of the type having a threaded connection between the strainer basket and strainer body.
One prior art sink strainer assembly generally includes a strainer body mounted to the sink drain opening and formed with a slot at the bottom, a strainer basket having a flexible stopper along its outer surface which is adapted to contact the interior wall of the strainer body, and a strainer post mounted to the strainer basket and having a stem at one end which extends beneath the strainer basket and is adapted to be placed in or out of engagement with the slot in the strainer body. By manipulating the post so that the stem aligns with and drops into the slot, the strainer basket is moved downwardly within the strainer body so that the flexible stopper engages the sides of the strainer body and creates a seal therebetween allowing the sink to hold liquid. To drain the sink of liquid, the post and strainer basket are lifted and turned 90.degree. so that the stem rests atop the slot in the strainer body. This lifts the flexible stopper of the strainer basket out of contact with the sides of the strainer body and breaks the seal therebetween.
One problem with this prior art design is that it is often difficult to manipulate the post so that it either drops into or rests atop the slot in the strainer body, particularly with slippery hands from dish water and the like. Another problem is that a poor seal is created between the rubber stopper of the strainer basket and the walls of the strainer body. This is because only the weight of the strainer basket urges the stopper into contact with the walls of the strainer body and most strainer baskets in use are lightweight.
One proposed solution to the problems of manipulating the strainer basket and post within the strainer body, and providing a good seal between the strainer basket and strainer body, has been to replace the slot in the bottom of the strainer body with a threaded bore and form the stem of the post which extends beneath the strainer basket with threads. The threaded stem of the post is long enough so that it can be partially threaded within the strainer body without the flexible stopper mounted on the outside of the strainer basket contacting the walls of the strainer body. It normally remains in this position during use of the sink to permit drainage. In order to seal the drain opening of the sink to wash dishes or the like, the post is simply tightened further into the threaded bore of the strainer body until the flexible stopper of in the strainer basket is secured against the walls of the strainer body. The threaded connection between the strainer basket and strainer body effects a much better seal than can be obtained by the weight of the strainer basket alone.
Sink strainer assemblies having a threaded connection between the post and strainer body, such as described above are shown, for example, in U.S. Pat. Nos. 2,225,693; 2,890,463; 3,800,339; and 3,777,320. One problem shared by all of these patented sink strainer assemblies is that too many parts are required to connect the strainer basket to the strainer body, which adds to the cost and increases the difficulty of assembling the device. In some designs, such as shown in U.S. Pat. No. 3,800,339, the post, stopper and strainer basket are not interconnected as a unit for insertion into the strainer body but are separate pieces. This can create problems of lost parts in the shipment of the strainer assembly, or misplacement of parts when the assembly is removed from the sink for cleaning or repair.